"Comcast selected the MX-series and T1600 for commercial services and metro regional network applications, but we would defer to Comcast as to whether this is a pure expansion or replacement," Hayes told InternetNews.com. "We're not at liberty to provide that level of detail about our customers' networks."

Comcast did not immediately respond to request for comment on this story. Juniper T1600 competes directly against the Cisco CRS-1, which was at the heart of its own work with the cable ISP.

Cisco said Comcast has been testing a new 100GbE interface for the CRS-1 over Comcast's infrastructure between Philadelphia and McLean, Va.

Cisco spokesperson Kevin Petschow explained to InternetNews.comthat the 100GbE technology test completed by Comcast and Cisco is consistent with the emerging standard established by two industry bodies -- the two-year-old IEEE 802.3 High Speed Study Group (HSSG) and the 802.3ba task force formed in January.

"The technology demonstration was completed over Comcast's production network," Petschow said. "However, to do this cost-effectively and at scale, it's still early days. The demo is compliant with 'HSSG' and the 802.3ba task force, but an industry-approved standardization is still roughly two years out."

"Cisco is working very actively in making that happen," he added.

Petschow also noted that Juniper's deal with Comcast for its competitive T1600 routers has no impact on Cisco's own relationship with the company.

From Juniper's point of view, it's rival's 100GbE test is not necessarily a bad thing.

"Juniper's MX-series have been deployed to support commercial services, and are now expected to be deployed in their metro regional networks," Hayes said. "We also see that demonstrations such as was announced today are important for the industry as well."

Hayes added that Juniper is also committed to 100GbE.

"We can't say specifically which customers we are working with, but I can assure you that Juniper is working closely with our customers to meet their needs in this area," he said. "We're confident we will deliver the capabilities required by our customers in line with the progress of the industry standards bodies."